US20230331595A1 - System and Method for Electrochemical Oxidation of Polyfluoroalkyl Substances in Water - Google Patents
System and Method for Electrochemical Oxidation of Polyfluoroalkyl Substances in Water Download PDFInfo
- Publication number
- US20230331595A1 US20230331595A1 US17/270,852 US201917270852A US2023331595A1 US 20230331595 A1 US20230331595 A1 US 20230331595A1 US 201917270852 A US201917270852 A US 201917270852A US 2023331595 A1 US2023331595 A1 US 2023331595A1
- Authority
- US
- United States
- Prior art keywords
- anode
- electrochemical cell
- water
- cathode
- concentration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims description 36
- 239000000126 substance Substances 0.000 title abstract description 5
- 238000006056 electrooxidation reaction Methods 0.000 title description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 38
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims abstract description 38
- SNGREZUHAYWORS-UHFFFAOYSA-N perfluorooctanoic acid Chemical compound OC(=O)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)F SNGREZUHAYWORS-UHFFFAOYSA-N 0.000 claims description 24
- 239000003792 electrolyte Substances 0.000 claims description 19
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 17
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 17
- 239000006260 foam Substances 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 15
- 238000007254 oxidation reaction Methods 0.000 claims description 11
- YFSUTJLHUFNCNZ-UHFFFAOYSA-N perfluorooctane-1-sulfonic acid Chemical compound OS(=O)(=O)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)F YFSUTJLHUFNCNZ-UHFFFAOYSA-N 0.000 claims description 11
- 230000003647 oxidation Effects 0.000 claims description 10
- 239000011148 porous material Substances 0.000 claims description 10
- 239000010936 titanium Substances 0.000 claims description 10
- 235000011152 sodium sulphate Nutrition 0.000 claims description 9
- 150000005857 PFAS Chemical class 0.000 claims description 7
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 5
- 238000010977 unit operation Methods 0.000 claims description 5
- 238000011144 upstream manufacturing Methods 0.000 claims description 5
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 3
- 229910010420 TinO2n-1 Inorganic materials 0.000 claims description 3
- 230000005661 hydrophobic surface Effects 0.000 claims description 3
- 229910001000 nickel titanium Inorganic materials 0.000 claims description 3
- 230000004044 response Effects 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 238000004891 communication Methods 0.000 claims description 2
- 101001136034 Homo sapiens Phosphoribosylformylglycinamidine synthase Proteins 0.000 claims 3
- 102100036473 Phosphoribosylformylglycinamidine synthase Human genes 0.000 claims 3
- 229910009848 Ti4O7 Inorganic materials 0.000 claims 2
- 239000010405 anode material Substances 0.000 description 11
- 239000007832 Na2SO4 Substances 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 150000001875 compounds Chemical class 0.000 description 6
- 230000007613 environmental effect Effects 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 230000006378 damage Effects 0.000 description 4
- 238000006115 defluorination reaction Methods 0.000 description 4
- 239000008151 electrolyte solution Substances 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 3
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- -1 carboxylate ions Chemical class 0.000 description 3
- 239000003651 drinking water Substances 0.000 description 3
- 235000020188 drinking water Nutrition 0.000 description 3
- 229910052731 fluorine Inorganic materials 0.000 description 3
- 239000011737 fluorine Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000002594 sorbent Substances 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- 230000004075 alteration Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 231100000693 bioaccumulation Toxicity 0.000 description 2
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 2
- 239000004327 boric acid Substances 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000003456 ion exchange resin Substances 0.000 description 2
- 229920003303 ion-exchange polymer Polymers 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000011002 quantification Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- WOCIAKWEIIZHES-UHFFFAOYSA-N ruthenium(iv) oxide Chemical compound O=[Ru]=O WOCIAKWEIIZHES-UHFFFAOYSA-N 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000006557 surface reaction Methods 0.000 description 2
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 241000282414 Homo sapiens Species 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-PWCQTSIFSA-N Tritiated water Chemical compound [3H]O[3H] XLYOFNOQVPJJNP-PWCQTSIFSA-N 0.000 description 1
- 230000002730 additional effect Effects 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000000872 buffer Substances 0.000 description 1
- IYRWEQXVUNLMAY-UHFFFAOYSA-N carbonyl fluoride Chemical compound FC(F)=O IYRWEQXVUNLMAY-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 238000005660 chlorination reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005518 electrochemistry Effects 0.000 description 1
- 239000012527 feed solution Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 125000005842 heteroatom Chemical group 0.000 description 1
- 238000004128 high performance liquid chromatography Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 238000004255 ion exchange chromatography Methods 0.000 description 1
- HTXDPTMKBJXEOW-UHFFFAOYSA-N iridium(IV) oxide Inorganic materials O=[Ir]=O HTXDPTMKBJXEOW-UHFFFAOYSA-N 0.000 description 1
- YADSGOSSYOOKMP-UHFFFAOYSA-N lead dioxide Inorganic materials O=[Pb]=O YADSGOSSYOOKMP-UHFFFAOYSA-N 0.000 description 1
- 238000004502 linear sweep voltammetry Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000002688 persistence Effects 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000010345 tape casting Methods 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
- C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/008—Control or steering systems not provided for elsewhere in subclass C02F
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/46104—Devices therefor; Their operating or servicing
- C02F1/46109—Electrodes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/46104—Devices therefor; Their operating or servicing
- C02F1/46109—Electrodes
- C02F2001/46133—Electrodes characterised by the material
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/46104—Devices therefor; Their operating or servicing
- C02F1/46109—Electrodes
- C02F2001/46152—Electrodes characterised by the shape or form
- C02F2001/46157—Perforated or foraminous electrodes
- C02F2001/46161—Porous electrodes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/36—Organic compounds containing halogen
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/46—Apparatus for electrochemical processes
- C02F2201/461—Electrolysis apparatus
- C02F2201/46105—Details relating to the electrolytic devices
- C02F2201/4612—Controlling or monitoring
- C02F2201/46125—Electrical variables
- C02F2201/4613—Inversing polarity
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/46—Apparatus for electrochemical processes
- C02F2201/461—Electrolysis apparatus
- C02F2201/46105—Details relating to the electrolytic devices
- C02F2201/4612—Controlling or monitoring
- C02F2201/46125—Electrical variables
- C02F2201/46135—Voltage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/001—Upstream control, i.e. monitoring for predictive control
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/003—Downstream control, i.e. outlet monitoring, e.g. to check the treating agents, such as halogens or ozone, leaving the process
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/02—Temperature
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/06—Controlling or monitoring parameters in water treatment pH
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/29—Chlorine compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/40—Liquid flow rate
Definitions
- One or more aspects relate generally to electrochemical water treatment.
- PFAS Per- and polyfluoroalkyl substances
- Sorption or filtration technologies have been commonly used to separate PFAS from impacted water (including wastewater, surface water, drinking water, and groundwater). Separation via sorbents or filters relies on sorption and other physical mechanisms that remove PFAS from water.
- the sorbents or filters (including ion exchange resin, reverse osmosis filters and activated carbon filters) will eventually become loaded with high concentrations of PFAS requiring regeneration of the sorbents or filters if they cannot be safely discharged or disposed of by other means.
- a method of treating water containing per- and polyfluoroalkyl substances is disclosed.
- the method may comprise introducing the water to an electrochemical cell comprising a cathode and a Magnéli phase titanium oxide anode having a porosity of at least about 25%, and applying a voltage to the anode in an amount sufficient to promote oxidation of the PFASs in order to produce treated water.
- PFASs per- and polyfluoroalkyl substances
- the PFASs may comprise perfluorooctane sulfonic acid (PFOS) or perfluorooctanoic acid (PFOA).
- PFOS perfluorooctane sulfonic acid
- PFOA perfluorooctanoic acid
- the anode may comprise Ti n O 2n-1 , where n ranges from 3 to 9 inclusive. In some specific aspects, the anode may comprise Ti 4 O 7 .
- the anode may comprise a mesh structure.
- the anode may comprise a foam structure.
- a foam anode may be characterized by a mean pore size of from about 100 ⁇ m to about 2 mm.
- the cathode may be made of a stainless steel, nickel alloy, titanium, or a dimensionally stable anode (DSA) material.
- the water is circulated between the cathode and the anode. In other aspects, the water may be circulated through the anode and cathode in series.
- the electrochemical cell may comprise a sodium sulfate electrolyte, e.g. a sodium sulfate electrolyte at a concentration of about 5 mM.
- the method may further comprise introducing the treated water to a downstream unit operation for further treatment.
- the method may further comprise monitoring a PFAS concentration, pH level, or other operational parameter upstream of the electrochemical cell.
- the method may further comprise adjusting the applied voltage in response to the monitored PFAS concentration.
- the method may further comprise monitoring a PFAS concentration, pH level, or other operational parameter downstream of the electrochemical cell.
- a water treatment system may comprise an electrochemical cell comprising a Magnéli phase titanium oxide anode having a porosity of at least about 25%, and a source of water comprising PFASs fluidly connected to an inlet of the electrochemical cell.
- the PFASs may comprise perfluorooctane sulfonic acid (PFOS) or perfluorooctanoic acid (PFOA).
- PFOS perfluorooctane sulfonic acid
- PFOA perfluorooctanoic acid
- the anode may comprise Ti 4 O 7 .
- the anode may comprise a mesh structure.
- the anode may comprise a foam structure.
- a foam anode may be characterized by a mean pore size of from about 100 ⁇ m to about 2 mm.
- the electrochemical cell may be constructed and arranged to circulate the water between the cathode and the anode.
- the electrochemical cell may be constructed and arranged to circulate the water through the cathode and the anode in series.
- the electrochemical cell may further comprise a sodium sulfate electrolyte, e.g. a sodium sulfate electrolyte at a concentration of about 5 mM.
- a sodium sulfate electrolyte e.g. a sodium sulfate electrolyte at a concentration of about 5 mM.
- the system may further comprise at least one concentration, pH, voltage, or other sensor positioned upstream and/or downstream of the electrochemical cell.
- the system may further comprise a controller in communication with the at least one sensor configured to adjust a voltage applied to the electrochemical cell.
- the anode of the electrochemical cell may be characterized by a hydrophobic surface.
- FIG. 1 illustrates oxygen overpotential of an anode material in accordance with one or more embodiments
- FIG. 2 A presents a schematic of a flow between electrodes (FBE) electrochemical cell arrangement in accordance with one or more embodiments.
- FIG. 2 B presents a schematic of a flow through electrodes (FTE) electrochemical cell arrangement in accordance with one or more embodiments.
- FTE flow through electrodes
- systems and methods relate to electrochemical treatment of water.
- electrochemistry may be applied for the removal of various negatively-charged contaminant molecules.
- PFASs per- and polyfluoroalkyl substances
- PFCs perfluorinated chemicals
- man-made chemical compounds are very stable and resilient to breakdown in the environment. They may also be highly water soluble because they carry a negative charge when dissolved. They were developed and widely used as a repellant and protective coating. Though they have now largely been phased out, elevated levels are still widespread.
- PFAS or PFC water contaminated with PFAS or PFC may be found in industrial communities where they were manufactured or used, as well as near airfields or military bases where firefighting drills were conducted. PFAS or PFC may also be found in remote locations via water or air migration. Many municipal water systems are undergoing aggressive testing and treatment. This invention is not limited to the types of negatively-charged and/or fluorinated compounds being treated.
- electrochemical techniques may be applied for the destruction of PFASs in water.
- cationic PFAS of PFC levels in water may be addressed.
- common PFCs such as perfluorooctanoic acid (PFOA) and/or perfluorooctane sulfonic acid (PFOS) may be removed from water via an electrochemical operation.
- PFOA perfluorooctanoic acid
- PFOS perfluorooctane sulfonic acid
- EPA Environmental Protection Agency developed revised guidelines in May 2016 of a combined lifetime exposure of 70 parts per trillion (PPT) for PFOS and PFOA. Federal, state, and/or private bodies may also issue relevant regulations.
- other approaches for PFC removal such as the use of ion exchange resin, may be used in conjunction with electrochemical treatment as described herein.
- product water as described herein may be potable.
- electrochemical treatment as described herein may find utility in the municipal water treatment market and may be used to produce drinking water.
- the disclosed techniques may be integrated with one or more pre- or post-treatment unit operations.
- an electrochemical cell may be used in conjunction with another water treatment approach such as ion exchange.
- an electrochemical cell may be used to degrade PFASs in water.
- the electrochemical cell may generally include two electrodes, a cathode and an anode.
- a reference electrode may also be used, for example, in proximity to the anode.
- the cathode may be constructed of various materials. Environmental conditions, e.g. pH level, and specific process requirements, e.g. those pertaining to cleaning or maintenance, may impact cathode selection.
- the cathode may be made of stainless steel, nickel alloy, titanium, or a dimensionally stable anode (DSA) material.
- the anode may be constructed of a material characterized by a high oxygen overpotential.
- Overpotential may generally relate to the potential difference (voltage) between a half-reaction's thermodynamically determined reduction potential and the potential at which a redox event is experimentally observed.
- the term may be directly related to an electrochemical cell's voltage efficiency.
- the anode may exhibit a preference for a surface reaction in water. Based on various physical characteristics and/or the chemical composition of the anode, water molecules may be repelled from the surface while non-polar organic pollutants may be easily absorbed. This may promote a direct oxidation reaction on the surface which may, for example, be particularly beneficial for the treatment of PFASs.
- the anode may be constructed of a Magnéli phase titanium oxide.
- Magnéli phase titanium oxide anodes may have superior performance towards oxygen evolution compared to other anodes. This may allow for the direct oxidation of PFASs on its surface. Additionally, in comparison to other electrodes with similar overpotential characteristics, Magnéli phase titanium oxide is less expensive than boron doped diamond (BDD), more robust than Ti/SnO 2 , and more environmentally friendly than Pb/PbO 2 .
- BDD boron doped diamond
- the anode material may generally have the formula Ti n O 2n-1 , where n ranges from 3 to 9 inclusive.
- the anode may be made of Ti 4 O 7 . Pure Ti 4 O 7 may be an attractive material for the application of advanced electrochemical oxidation.
- FIG. 1 presents Linear Sweep Voltammetry (LSV) data illustrating the overpotential pertaining to a Magnéli phase titanium oxide (Ti 4 O 7 ) anode.
- LSV Linear Sweep Voltammetry
- Equations 1 through 5 below may represent the underlying mechanism for electrochemical PFAS removal with a Magnéli phase titanium oxide (Ti 4 O 7 ) anode.
- the reaction may generally be characterized as a Kolbe-type oxidation.
- the reaction initiates from direct oxidation of carboxylate ions to carboxylate radicals (Eq. 1) on a Ti 4 O 7 surface by applying a sufficient positive voltage.
- the carboxylate radicals are subsequently decarboxylated to perfluoroalkyl radicals (Eq. 2).
- the perfluoroalkyl radicals are converted to perfluoro alcohols (Eq.
- reactions 1 to 5 may generally be repeated until all carbon from PFASs are eventually stripped off to inorganic CO 2 , H + , and F ⁇ .
- various material properties of the Magnéli phase titanium oxide anode may be optimized.
- a pore structure and/or distribution of the material may be selected in order to promote mass transfer of contaminants for surface reaction as well as to ensure sufficient physical area for reaction.
- the anode may have a foam structure.
- the anode material may have a total porosity of about 25%, 30%, 40%, 50%, 60%, 70% or higher. In at least some embodiments, the total porosity may be about 50% or greater.
- the anode material may have a pore size on the micrometer to millimeter scale.
- the anode material may have a mean pore size ranging from about 100 ⁇ m to about 2 mm, i.e. from about 200 ⁇ m to about 1.8 mm; 300 ⁇ m to about 1.7 mm, 400 ⁇ m to about 1.6 mm, or 500 ⁇ m to about 1.5 mm.
- the Magnéli phase titanium oxide may be an anode material commercially available from Magnéli Materials, LLC.
- the Magnéli phase titanium oxide anode may be used in an electrochemical reactor.
- the anode may be formed in a variety of shapes, for example, planar or circular.
- the anode may be characterized by a mesh or foam structure, such as may be associated with a higher active surface area, pore structure, and/or distribution.
- various reactor flow designs may be implemented. Selection may be based on various operational parameters, for example, based on a concentration of the PFAS in water to be treated.
- a flow between electrode (FBE) configuration may be used as illustrated in FIG. 2 A .
- a flow through electrode (FTE) configuration may be used as illustrated in FIG. 2 B .
- a FBE configuration may be appropriate for relatively high concentrations of PFAS while a FTE configuration may be used for relatively low concentrations of PFAS, such as for drinking water treatment.
- various conventional electrolytes may be used in the electrochemical cell.
- sodium sulfate may be used as the electrolyte.
- An electrolyte concentration may impact performance of the electrochemical cell. The electrolyte concentration may be selected in order to minimize the impact of competitive side reactions, for example, water oxidation and/or chlorination on the anode. Thus, the electrolyte concentration may be adjusted in order to maximize the current efficiency of the electrochemical cell with respect to PFAS oxidation.
- an electrolyte, e.g. sodium sulfate, at a concentration of at least about 5 mM may be used. In at least some non-limiting embodiments, an electrolyte, e.g. sodium sulfate, at a concentration of less than about 100 mM may be used.
- current density may be a significant operational parameter and may be optimized for electrochemical cell efficiency.
- Lower current density may require a lower cell voltage with a potential benefit in terms of energy consumption per ppm PFOA removal.
- the overall cell voltage must be sufficient in terms of anode potential in order to oxidize PFASs.
- high efficiency while maintaining a high oxidation rate may be achieved by implementing a high surface area anode.
- a high porosity anode e.g. a foam anode, may beneficially provide high surface area to introduce high current for PFAS destruction.
- a current density of about 1-2 mA/cm 2 may be used.
- a current density of less than about 10 mA/cm 2 may be used.
- a process stream containing an elevated PFAS level may be introduced to an electrochemical cell for treatment.
- the electrochemical cell may include a Magnéli phase titanium oxide anode as described herein.
- the anode material may have a porosity of at least about 25%.
- the anode material may have a mean pore size ranging from about 100 ⁇ m to about 2 mm.
- the electrochemical cell may include an electrolyte as described herein and a voltage may be applied to the anode as described herein to provide a desired level of treatment.
- Various pre-treatment and/or post-treatment unit operations may also be integrated.
- a product stream may be directed to a further unit operation for additional treatment, sent to a point of use, or otherwise discharged. Polarity of the electrochemical cell may be reversed periodically if desired such as to facilitate maintenance.
- one or more sensors may measure a level of PFAS/PFC upstream and/or downstream of the electrochemical cell.
- a controller 150 may receive input from the sensor(s) in order to monitor PFAS/PFC levels, intermittently or continuously. Monitoring may be in real-time or with lag, either onsite or remotely.
- a detected PFAS/PFC level may be compared to a threshold level that may be considered unacceptable, such as may be dictated by a controlling regulatory body. Additional properties such as pH, flow rate, voltage, temperature, and other concentrations may be monitored by various interconnected or interrelational sensors throughout the system.
- the controller may send one or more control signals to adjust various operational parameters, i.e. applied voltage, in response to sensor input.
- a Magnéli phase titanium oxide anode may be fabricated.
- Various conventional fabrication techniques commonly known to those of skill in the art may be implemented.
- Current Ti 4 O 7 electrodes are generally obtained by oxidation and then reduction of titanium metal at certain temperatures and oxidant levels. The resulting electrode is generally brittle with nonuniform appearance. Thus, its capacity to resist mechanical wearing is limited which directly limits its lifetime for anode applications.
- pure Ti 4 O 7 powder with a weight percent of about 80% to about 95% may be mixed with a binder comprising PTFE or PVDF.
- the ratio of metal to plastic binder may be varied depending on factors such as surface affinity towards different liquids. Generally, a hydrophobic surface and lower conductivity may be favored when more binder is added into the electrode/binder mixture.
- the Ti 4 O 7 powder may be ball milled in order to achieve a desired particle size.
- the metal powder may be mixed with either PTFE or PVDF.
- the final electrode can then be fabricated on a titanium substrate by methods such as injection molding, painting, or doctor blading. This invention is not limited by the method of electrode fabrication.
- a defluorination ratio (%) is a term that may be used to describe the extent to which organic PFAS has been mineralized to release inorganic F ⁇ . It is the ratio of actual F ⁇ detected by instrument after the treatment divided by total F in the original organic PFAS.
- Reaction Reaction voltage 3 V voltage: 5.5 V Ti 4 O 7 F ⁇ Not detected 32% DSA (Pt/Ti, IrO 2 /Ti, RuO 2 /Ti) F ⁇ Not detected F ⁇ Not detected BDD F ⁇ Not detected 57% Ti 4 O 7 (100 mM Na 2 SO 4 ) F ⁇ Not detected F ⁇ Not detected
- the anodes were G1 foam Ti 4 O 7 anodes commercially available from Magnéli Materials, LLC.
- the anodes had a pore size of from about 100 um to about 2 mm. Porosity of the anode was estimated to be about 50%.
- the anodes had dimensions of about 3 ⁇ 3 ⁇ 0.5 cm and were placed in the test cell at an inter-electrode distance of about 3 cm.
- the current for the main experiments was adjusted until the cell voltage was larger than 6V.
- 25 mA was applied on the anode while a cell voltage of about 6V was recorded.
- the primary tests were performed at room temperature (about 25° C.) and at a neutral pH level (about 6.8-7.2) in a batch process (100 mL beaker). An 80 ml Na 2 SO 4 solution without any pH adjustment was used for the electrolyte.
- Quantification of F ⁇ anion was achieved by Ion Chromatography (Metrohm 850 professional IC) coupled with Metrosep A column.
- the mobile phase was 3.2 mM Na 2 CO 3 and 1 mM NaHCO 3 .
- Quantification of PFOA anion was achieved by the same IC, however, employing a ProntoSlL HPLC column and a solution consisting of 10 mM boric acid and 20 wt % acetonitrile (pH was adjusted to 8 by 4M NaOH) as the mobile phase.
- the F ⁇ recovery data refers to total F ⁇ that has been recovered from PFOA and its by-products.
- the voltage of the cell is high enough to remove some F ⁇ from water but the F ⁇ recovery data is significant in that it demonstrates that PFAS is being destroyed in water. It is also worth noting that the potential higher than 5V vs. RHE is sufficient to convert F ⁇ anion to other forms of fluorine (e.g. F 2 gas) which may also have impacted the accuracy of this data.
- the term “plurality” refers to two or more items or components.
- the terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e., to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phrases “consisting of” and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims.
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
Abstract
Description
- This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 62/721,647 as filed on Aug. 23, 2018 and titled “SYSTEM AND METHOD FOR ELECTROCHEMICAL OXIDATION OF POLYFLUOROALKYL SUBSTANCES IN WATER,” the entire disclosure of which is hereby incorporated herein by reference in its entirety for all purposes.
- One or more aspects relate generally to electrochemical water treatment.
- Per- and polyfluoroalkyl substances (PFAS) are organic compounds consisting of fluorine, carbon and heteroatoms such as oxygen, nitrogen and sulfur. The hydrophobicity of fluorocarbons and extreme electronegativity of fluorine give these and similar compounds unusual properties. Initially, many of these compounds were used as gases in the fabrication of integrated circuits. The ozone destroying properties of these molecules restricted their use and resulted in methods to prevent their release into the atmosphere. But other PFAS such as fluoro-surfactants have become increasingly popular. Although used in relatively small amounts, these compounds are readily released into the environment where their extreme hydrophobicity as well as negligible rates of natural decomposition results in environmental persistence and bioaccumulation. It appears as if even low levels of bioaccumulation may lead to serious health consequences for contaminated animals such as human beings, the young being especially susceptible. The environmental effects of these compounds on plants and microbes are as yet largely unknown. Nevertheless, serious efforts to limit the environmental release of PFAS are now commencing.
- Sorption or filtration technologies have been commonly used to separate PFAS from impacted water (including wastewater, surface water, drinking water, and groundwater). Separation via sorbents or filters relies on sorption and other physical mechanisms that remove PFAS from water. The sorbents or filters (including ion exchange resin, reverse osmosis filters and activated carbon filters) will eventually become loaded with high concentrations of PFAS requiring regeneration of the sorbents or filters if they cannot be safely discharged or disposed of by other means.
- In accordance with one or more aspects, a method of treating water containing per- and polyfluoroalkyl substances (PFASs) is disclosed. The method may comprise introducing the water to an electrochemical cell comprising a cathode and a Magnéli phase titanium oxide anode having a porosity of at least about 25%, and applying a voltage to the anode in an amount sufficient to promote oxidation of the PFASs in order to produce treated water.
- In some aspects, the PFASs may comprise perfluorooctane sulfonic acid (PFOS) or perfluorooctanoic acid (PFOA).
- In some aspects, the anode may comprise TinO2n-1, where n ranges from 3 to 9 inclusive. In some specific aspects, the anode may comprise Ti4O7. The anode may comprise a mesh structure. The anode may comprise a foam structure. A foam anode may be characterized by a mean pore size of from about 100 μm to about 2 mm. The cathode may be made of a stainless steel, nickel alloy, titanium, or a dimensionally stable anode (DSA) material.
- In some aspects, the water is circulated between the cathode and the anode. In other aspects, the water may be circulated through the anode and cathode in series.
- In some aspects, the electrochemical cell may comprise a sodium sulfate electrolyte, e.g. a sodium sulfate electrolyte at a concentration of about 5 mM.
- In some aspects, the method may further comprise introducing the treated water to a downstream unit operation for further treatment. The method may further comprise monitoring a PFAS concentration, pH level, or other operational parameter upstream of the electrochemical cell. The method may further comprise adjusting the applied voltage in response to the monitored PFAS concentration. The method may further comprise monitoring a PFAS concentration, pH level, or other operational parameter downstream of the electrochemical cell.
- In accordance with one or more aspects, a water treatment system is disclosed. The system may comprise an electrochemical cell comprising a Magnéli phase titanium oxide anode having a porosity of at least about 25%, and a source of water comprising PFASs fluidly connected to an inlet of the electrochemical cell.
- In some aspects, the PFASs may comprise perfluorooctane sulfonic acid (PFOS) or perfluorooctanoic acid (PFOA). The anode may comprise Ti4O7. The anode may comprise a mesh structure. The anode may comprise a foam structure. A foam anode may be characterized by a mean pore size of from about 100 μm to about 2 mm.
- In some aspects, the electrochemical cell may be constructed and arranged to circulate the water between the cathode and the anode. The electrochemical cell may be constructed and arranged to circulate the water through the cathode and the anode in series.
- In some aspects, the electrochemical cell may further comprise a sodium sulfate electrolyte, e.g. a sodium sulfate electrolyte at a concentration of about 5 mM.
- In some aspects, the system may further comprise at least one concentration, pH, voltage, or other sensor positioned upstream and/or downstream of the electrochemical cell. The system may further comprise a controller in communication with the at least one sensor configured to adjust a voltage applied to the electrochemical cell.
- In some aspects, the anode of the electrochemical cell may be characterized by a hydrophobic surface.
- The disclosure contemplates all combinations of any one or more of the foregoing aspects and/or embodiments, as well as combinations with any one or more of the embodiments set forth in the detailed description and any examples.
- Certain illustrative features and examples are described below with reference to the accompanying figures in which:
-
FIG. 1 illustrates oxygen overpotential of an anode material in accordance with one or more embodiments; -
FIG. 2A presents a schematic of a flow between electrodes (FBE) electrochemical cell arrangement in accordance with one or more embodiments; and -
FIG. 2B presents a schematic of a flow through electrodes (FTE) electrochemical cell arrangement in accordance with one or more embodiments. - It will be recognized by the person of ordinary skill in the art, given the benefit of this disclosure, that the figures are purely for illustrative purposes. Other features may be present in the embodiments disclosed herein without departing from the scope of the description.
- In accordance with one or more embodiments, systems and methods relate to electrochemical treatment of water. In some embodiments, electrochemistry may be applied for the removal of various negatively-charged contaminant molecules. Notable amongst such molecules are per- and polyfluoroalkyl substances (PFASs), also referred to as perfluorinated chemicals (PFCs), that are present in wastewater. These man-made chemical compounds are very stable and resilient to breakdown in the environment. They may also be highly water soluble because they carry a negative charge when dissolved. They were developed and widely used as a repellant and protective coating. Though they have now largely been phased out, elevated levels are still widespread. For example, water contaminated with PFAS or PFC may be found in industrial communities where they were manufactured or used, as well as near airfields or military bases where firefighting drills were conducted. PFAS or PFC may also be found in remote locations via water or air migration. Many municipal water systems are undergoing aggressive testing and treatment. This invention is not limited to the types of negatively-charged and/or fluorinated compounds being treated.
- In some non-limiting embodiments, electrochemical techniques may be applied for the destruction of PFASs in water. In some embodiments, cationic PFAS of PFC levels in water may be addressed. In some specific non-limiting embodiments, common PFCs such as perfluorooctanoic acid (PFOA) and/or perfluorooctane sulfonic acid (PFOS) may be removed from water via an electrochemical operation. The U.S. Environmental Protection Agency (EPA) developed revised guidelines in May 2016 of a combined lifetime exposure of 70 parts per trillion (PPT) for PFOS and PFOA. Federal, state, and/or private bodies may also issue relevant regulations. In some embodiments, other approaches for PFC removal, such as the use of ion exchange resin, may be used in conjunction with electrochemical treatment as described herein.
- In accordance with one or more embodiments, product water as described herein may be potable. In at least some embodiments, electrochemical treatment as described herein may find utility in the municipal water treatment market and may be used to produce drinking water. The disclosed techniques may be integrated with one or more pre- or post-treatment unit operations. For example, an electrochemical cell may be used in conjunction with another water treatment approach such as ion exchange.
- In accordance with one or more embodiments, an electrochemical cell may be used to degrade PFASs in water. The electrochemical cell may generally include two electrodes, a cathode and an anode. A reference electrode may also be used, for example, in proximity to the anode.
- In accordance with one or more embodiments, the cathode may be constructed of various materials. Environmental conditions, e.g. pH level, and specific process requirements, e.g. those pertaining to cleaning or maintenance, may impact cathode selection. In some non-limiting embodiments, the cathode may be made of stainless steel, nickel alloy, titanium, or a dimensionally stable anode (DSA) material.
- In accordance with one or more embodiments, the anode may be constructed of a material characterized by a high oxygen overpotential. Overpotential may generally relate to the potential difference (voltage) between a half-reaction's thermodynamically determined reduction potential and the potential at which a redox event is experimentally observed. The term may be directly related to an electrochemical cell's voltage efficiency.
- In accordance with one or more embodiments, the anode may exhibit a preference for a surface reaction in water. Based on various physical characteristics and/or the chemical composition of the anode, water molecules may be repelled from the surface while non-polar organic pollutants may be easily absorbed. This may promote a direct oxidation reaction on the surface which may, for example, be particularly beneficial for the treatment of PFASs.
- In accordance with one or more embodiments, the anode may be constructed of a Magnéli phase titanium oxide. Magnéli phase titanium oxide anodes may have superior performance towards oxygen evolution compared to other anodes. This may allow for the direct oxidation of PFASs on its surface. Additionally, in comparison to other electrodes with similar overpotential characteristics, Magnéli phase titanium oxide is less expensive than boron doped diamond (BDD), more robust than Ti/SnO2, and more environmentally friendly than Pb/PbO2.
- In some embodiments, the anode material may generally have the formula TinO2n-1, where n ranges from 3 to 9 inclusive. In some specific non-limiting embodiments, the anode may be made of Ti4O7. Pure Ti4O7 may be an attractive material for the application of advanced electrochemical oxidation.
FIG. 1 presents Linear Sweep Voltammetry (LSV) data illustrating the overpotential pertaining to a Magnéli phase titanium oxide (Ti4O7) anode. - In accordance with one or more embodiments,
Equations 1 through 5 below may represent the underlying mechanism for electrochemical PFAS removal with a Magnéli phase titanium oxide (Ti4O7) anode. The reaction may generally be characterized as a Kolbe-type oxidation. The reaction initiates from direct oxidation of carboxylate ions to carboxylate radicals (Eq. 1) on a Ti4O7 surface by applying a sufficient positive voltage. The carboxylate radicals are subsequently decarboxylated to perfluoroalkyl radicals (Eq. 2). By coupling with hydroxyl free radicals which are anodically generated on the Ti4O7 surface, the perfluoroalkyl radicals are converted to perfluoro alcohols (Eq. 3) which further defluorinate to perfluoro carbonyl fluoride (Eq. 4) and finally hydrolyze to a perfluorocarboxylic as a byproduct by losing one carbon in the chain (Eq. 5).Reactions 1 to 5 may generally be repeated until all carbon from PFASs are eventually stripped off to inorganic CO2, H+, and F−. -
Ti4O7+C7F15COO−→Ti4O7+C7F15COO·+e − (1) -
C7F15COO·→C7F15·+CO2 (2) -
C7F15·+HO·→C7F15OH (3) -
C7F15OH→C6F13COF+H++F− (4) -
C6F13COF+H2O→C6F13COO−+H+F− (5) - In accordance with one or more embodiments, various material properties of the Magnéli phase titanium oxide anode may be optimized. For example, a pore structure and/or distribution of the material may be selected in order to promote mass transfer of contaminants for surface reaction as well as to ensure sufficient physical area for reaction. In at least some embodiments, the anode may have a foam structure. In some embodiments, the anode material may have a total porosity of about 25%, 30%, 40%, 50%, 60%, 70% or higher. In at least some embodiments, the total porosity may be about 50% or greater. In some embodiments, the anode material may have a pore size on the micrometer to millimeter scale. In at least some embodiments, the anode material may have a mean pore size ranging from about 100 μm to about 2 mm, i.e. from about 200 μm to about 1.8 mm; 300 μm to about 1.7 mm, 400 μm to about 1.6 mm, or 500 μm to about 1.5 mm. In at least some embodiments, the Magnéli phase titanium oxide may be an anode material commercially available from Magnéli Materials, LLC.
- In accordance with one or more embodiments, the Magnéli phase titanium oxide anode may be used in an electrochemical reactor. The anode may be formed in a variety of shapes, for example, planar or circular. In at least some preferred embodiments, the anode may be characterized by a mesh or foam structure, such as may be associated with a higher active surface area, pore structure, and/or distribution.
- In accordance with one or more embodiments, various reactor flow designs may be implemented. Selection may be based on various operational parameters, for example, based on a concentration of the PFAS in water to be treated. In some embodiments, a flow between electrode (FBE) configuration may be used as illustrated in
FIG. 2A . In other embodiments, a flow through electrode (FTE) configuration may be used as illustrated inFIG. 2B . A FBE configuration may be appropriate for relatively high concentrations of PFAS while a FTE configuration may be used for relatively low concentrations of PFAS, such as for drinking water treatment. - In accordance with one or more embodiments, various conventional electrolytes may be used in the electrochemical cell. For example, sodium sulfate may be used as the electrolyte. An electrolyte concentration may impact performance of the electrochemical cell. The electrolyte concentration may be selected in order to minimize the impact of competitive side reactions, for example, water oxidation and/or chlorination on the anode. Thus, the electrolyte concentration may be adjusted in order to maximize the current efficiency of the electrochemical cell with respect to PFAS oxidation. In some non-limiting embodiments, an electrolyte, e.g. sodium sulfate, at a concentration of at least about 5 mM may be used. In at least some non-limiting embodiments, an electrolyte, e.g. sodium sulfate, at a concentration of less than about 100 mM may be used.
- Likewise, current density may be a significant operational parameter and may be optimized for electrochemical cell efficiency. Lower current density may require a lower cell voltage with a potential benefit in terms of energy consumption per ppm PFOA removal. However, the overall cell voltage must be sufficient in terms of anode potential in order to oxidize PFASs. According to at least some embodiments, high efficiency while maintaining a high oxidation rate may be achieved by implementing a high surface area anode. A high porosity anode, e.g. a foam anode, may beneficially provide high surface area to introduce high current for PFAS destruction. In some non-limiting embodiments, a current density of about 1-2 mA/cm2 may be used. In at least some non-limiting embodiments, a current density of less than about 10 mA/cm2 may be used.
- In operation, a process stream containing an elevated PFAS level may be introduced to an electrochemical cell for treatment. The electrochemical cell may include a Magnéli phase titanium oxide anode as described herein. The anode material may have a porosity of at least about 25%. The anode material may have a mean pore size ranging from about 100 μm to about 2 mm. The electrochemical cell may include an electrolyte as described herein and a voltage may be applied to the anode as described herein to provide a desired level of treatment. Various pre-treatment and/or post-treatment unit operations may also be integrated. A product stream may be directed to a further unit operation for additional treatment, sent to a point of use, or otherwise discharged. Polarity of the electrochemical cell may be reversed periodically if desired such as to facilitate maintenance.
- In accordance with one or more embodiments, one or more sensors may measure a level of PFAS/PFC upstream and/or downstream of the electrochemical cell. A controller 150 may receive input from the sensor(s) in order to monitor PFAS/PFC levels, intermittently or continuously. Monitoring may be in real-time or with lag, either onsite or remotely. A detected PFAS/PFC level may be compared to a threshold level that may be considered unacceptable, such as may be dictated by a controlling regulatory body. Additional properties such as pH, flow rate, voltage, temperature, and other concentrations may be monitored by various interconnected or interrelational sensors throughout the system. The controller may send one or more control signals to adjust various operational parameters, i.e. applied voltage, in response to sensor input.
- In accordance with one or more embodiments, a Magnéli phase titanium oxide anode may be fabricated. Various conventional fabrication techniques commonly known to those of skill in the art may be implemented. Current Ti4O7 electrodes are generally obtained by oxidation and then reduction of titanium metal at certain temperatures and oxidant levels. The resulting electrode is generally brittle with nonuniform appearance. Thus, its capacity to resist mechanical wearing is limited which directly limits its lifetime for anode applications.
- In accordance with one or more non-limiting embodiments, pure Ti4O7 powder with a weight percent of about 80% to about 95% may be mixed with a binder comprising PTFE or PVDF. The ratio of metal to plastic binder may be varied depending on factors such as surface affinity towards different liquids. Generally, a hydrophobic surface and lower conductivity may be favored when more binder is added into the electrode/binder mixture.
- Prior to electrode fabrication, the Ti4O7 powder may be ball milled in order to achieve a desired particle size. The metal powder may be mixed with either PTFE or PVDF. The final electrode can then be fabricated on a titanium substrate by methods such as injection molding, painting, or doctor blading. This invention is not limited by the method of electrode fabrication.
- The function and advantages of these and other embodiments will be more fully understood from the following examples. The examples are intended to be illustrative in nature and are not to be considered as limiting the scope of the materials, systems, and methods discussed herein.
- Experiments were performed to explore the effect of anode material selection and voltage on defluorination efficiency in an electrochemical cell. A defluorination ratio (%) is a term that may be used to describe the extent to which organic PFAS has been mineralized to release inorganic F−. It is the ratio of actual F− detected by instrument after the treatment divided by total F in the original organic PFAS.
- Three different types of anode materials were tested: DSA, BDD, and Ti4O7. For each test, 80 mL of a feed solution having a 10 ppm PFOA concentration was introduced to a test cell. A 5 mM Na2SO4 solution was used as the electrolyte. A 25 mA current was applied over a reaction time of about 20 minutes. The Ti4O7 anode was also tested with a 100 mM Na2SO4 electrolyte solution.
- The related data is presented in Table 1. A higher De-F value (%) indicated better treatment performance. No defluorination was detected with the high concentration electrolyte solution. 3V cell voltage was insufficient to accomplish defluorination with any of the anodes. Ti4O7 was a very effective anode, performing competitively with BDD, and would be a viable option for anode material depending on PFAS removal requirements, particularly in view of its robustness, lower cost, and environmental friendliness.
-
TABLE 1 Reaction Reaction voltage: 3 V voltage: 5.5 V Ti4O7 F− Not detected 32% DSA (Pt/Ti, IrO2/Ti, RuO2/Ti) F− Not detected F− Not detected BDD F− Not detected 57% Ti4O7 (100 mM Na2SO4) F− Not detected F− Not detected - Testing was conducted on Ti4O7 anodes at varying PFOA feed concentrations and at varying electrolyte concentrations. The anodes were G1 foam Ti4O7 anodes commercially available from Magnéli Materials, LLC. The anodes had a pore size of from about 100 um to about 2 mm. Porosity of the anode was estimated to be about 50%. The anodes had dimensions of about 3×3×0.5 cm and were placed in the test cell at an inter-electrode distance of about 3 cm.
- Preliminary tests were performed to determine an appropriate cell voltage for PFOA destruction. The data indicated that F− anion was only capable to be detected at a potential higher than or equal to +4.5V vs. Ag/AgCl (equivalent to 5.1V vs. RHE) in 5 mM Na2SO4 electrolyte in a 1-hour experiment. This corresponded to an overall cell voltage of about 6V when the distance between cathode and anode was 3 cm. The cathode used throughout the preliminary experiments was Pt coated titanium.
- Thus, in order to promote Kolbe type oxidation, the current for the main experiments was adjusted until the cell voltage was larger than 6V. In this case, 25 mA was applied on the anode while a cell voltage of about 6V was recorded.
- The primary tests were performed at room temperature (about 25° C.) and at a neutral pH level (about 6.8-7.2) in a batch process (100 mL beaker). An 80 ml Na2SO4 solution without any pH adjustment was used for the electrolyte.
- The data is presented in Table 2. The use of a 0.1M electrolyte solution did not result in PFOA removal. The 5 mM electrolyte solution was effective at treating both the low and high PFOA concentration feeds.
- Quantification of F− anion was achieved by Ion Chromatography (Metrohm 850 professional IC) coupled with Metrosep A column. The mobile phase was 3.2 mM Na2CO3 and 1 mM NaHCO3. Quantification of PFOA anion was achieved by the same IC, however, employing a ProntoSlL HPLC column and a solution consisting of 10 mM boric acid and 20 wt % acetonitrile (pH was adjusted to 8 by 4M NaOH) as the mobile phase.
- The F− recovery data refers to total F− that has been recovered from PFOA and its by-products. In the PFAS destruction process, the voltage of the cell is high enough to remove some F− from water but the F− recovery data is significant in that it demonstrates that PFAS is being destroyed in water. It is also worth noting that the potential higher than 5V vs. RHE is sufficient to convert F− anion to other forms of fluorine (e.g. F2 gas) which may also have impacted the accuracy of this data.
- The associated energy consumption was much higher in connection with the low PFOA concentration feed as mass transport is limited when PFOA concentration is low.
-
TABLE 2 PFOA removal rate Percentage of measured by PFOA IC employing Energy removal boric acid consumption/ppm Feeding based on F− buffer as the PFOA removal Electrode Electrolyte PFOA (ppm) recovery middle phase (kwh/m3/ppm) Ti4O7 foam 5 mM Na2SO4 50 72% 99% 2.4 electrode from Magneli Materials Ti4O7 foam 5 mM Na2SO4 10 50% 99% 7.2 electrode from Magneli Materials Ti4O7 foam 0.1M Na2SO4 50 N.A. No removal N.A. electrode from Magneli Materials - The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used herein, the term “plurality” refers to two or more items or components. The terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e., to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phrases “consisting of” and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims. Use of ordinal terms such as “first,” “second,” “third,” and the like in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.
- Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Any feature described in any embodiment may be included in or substituted for any feature of any other embodiment. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.
- Those skilled in the art should appreciate that the parameters and configurations described herein are exemplary and that actual parameters and/or configurations will depend on the specific application in which the disclosed methods and materials are used. Those skilled in the art should also recognize or be able to ascertain, using no more than routine experimentation, equivalents to the specific embodiments disclosed.
Claims (27)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US17/270,852 US20230331595A1 (en) | 2018-08-23 | 2019-08-23 | System and Method for Electrochemical Oxidation of Polyfluoroalkyl Substances in Water |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201862721647P | 2018-08-23 | 2018-08-23 | |
US17/270,852 US20230331595A1 (en) | 2018-08-23 | 2019-08-23 | System and Method for Electrochemical Oxidation of Polyfluoroalkyl Substances in Water |
PCT/US2019/047922 WO2020041712A1 (en) | 2018-08-23 | 2019-08-23 | System and method for electrochemical oxidation of polyfluoroalkyl substances in water |
Publications (1)
Publication Number | Publication Date |
---|---|
US20230331595A1 true US20230331595A1 (en) | 2023-10-19 |
Family
ID=69591105
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/270,852 Pending US20230331595A1 (en) | 2018-08-23 | 2019-08-23 | System and Method for Electrochemical Oxidation of Polyfluoroalkyl Substances in Water |
Country Status (5)
Country | Link |
---|---|
US (1) | US20230331595A1 (en) |
EP (1) | EP3841069A4 (en) |
AU (1) | AU2019325635A1 (en) |
CA (1) | CA3107792A1 (en) |
WO (1) | WO2020041712A1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20210206670A1 (en) * | 2019-09-27 | 2021-07-08 | Auburn University | Compositions and methods for removal of per- and polyfluoroalkyl substances (pfas) |
CN112479447B (en) * | 2020-11-19 | 2022-08-05 | 河海大学 | Device and method for removing halogen-containing organic matters in water |
CN114275857A (en) * | 2021-12-06 | 2022-04-05 | 澳门大学 | Electrochemical wastewater treatment device and application thereof |
CN114715978B (en) * | 2022-02-21 | 2023-04-07 | 江南大学 | Application of electrochemical cathode of MOS (metal oxide semiconductor) for removing perfluorinated compounds by using hydrated electrons generated by cathode |
CN115849511A (en) * | 2022-10-28 | 2023-03-28 | 清华大学 | Method for treating waste water containing perfluoro compound |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4399020A (en) * | 1981-07-24 | 1983-08-16 | Diamond Shamrock Corporation | Device for waste water treatment |
US20070175766A1 (en) * | 2003-08-08 | 2007-08-02 | Pionetics Corporation | Regeneration of electrolytic ion exchange cells |
US20120055807A1 (en) * | 2009-03-09 | 2012-03-08 | Andreas Fath | Methods for decomposing partially fluorinated and perfluorinated surfactants |
US20190185352A1 (en) * | 2016-09-12 | 2019-06-20 | Aecom (Delaware Corporation) | Use of electrochemical oxidation for treatment of per-and polyfluoroalkyl substances (pfas) in waste generated from sorbent and resin regeneration processes |
US20190185351A1 (en) * | 2016-08-19 | 2019-06-20 | University Of Georgia Research Foundation, Inc. | Methods and systems for electrochemical oxidation of polyfluoroalkyl and perfluroalkyl contaminants |
US20190315661A1 (en) * | 2016-12-20 | 2019-10-17 | Saint-Gobain Centre De Recherches Et D'etudes Europeen | Porous ceramic products of titanium sub-oxides |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
HUP0104664A2 (en) * | 1998-12-07 | 2002-03-28 | Zappi Water Purification Systems, Inc. | Electrolytic apparatus, methods for purification of aqueous solutions and synthesis of chemicals |
CA2336507C (en) * | 2001-02-14 | 2006-06-27 | National Research Council Of Canada | Flow-through electrochemical reactor for wastewater treatment |
US20050221163A1 (en) * | 2004-04-06 | 2005-10-06 | Quanmin Yang | Nickel foam and felt-based anode for solid oxide fuel cells |
EP3538494A4 (en) * | 2016-11-10 | 2020-07-15 | The University of Massachusetts | A method for electrochemical treatment of water |
-
2019
- 2019-08-23 EP EP19851913.4A patent/EP3841069A4/en active Pending
- 2019-08-23 AU AU2019325635A patent/AU2019325635A1/en active Pending
- 2019-08-23 WO PCT/US2019/047922 patent/WO2020041712A1/en unknown
- 2019-08-23 US US17/270,852 patent/US20230331595A1/en active Pending
- 2019-08-23 CA CA3107792A patent/CA3107792A1/en active Pending
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4399020A (en) * | 1981-07-24 | 1983-08-16 | Diamond Shamrock Corporation | Device for waste water treatment |
US20070175766A1 (en) * | 2003-08-08 | 2007-08-02 | Pionetics Corporation | Regeneration of electrolytic ion exchange cells |
US20120055807A1 (en) * | 2009-03-09 | 2012-03-08 | Andreas Fath | Methods for decomposing partially fluorinated and perfluorinated surfactants |
US20190185351A1 (en) * | 2016-08-19 | 2019-06-20 | University Of Georgia Research Foundation, Inc. | Methods and systems for electrochemical oxidation of polyfluoroalkyl and perfluroalkyl contaminants |
US20190185352A1 (en) * | 2016-09-12 | 2019-06-20 | Aecom (Delaware Corporation) | Use of electrochemical oxidation for treatment of per-and polyfluoroalkyl substances (pfas) in waste generated from sorbent and resin regeneration processes |
US20190315661A1 (en) * | 2016-12-20 | 2019-10-17 | Saint-Gobain Centre De Recherches Et D'etudes Europeen | Porous ceramic products of titanium sub-oxides |
Non-Patent Citations (2)
Title |
---|
Duan et al, "Fabrication of a hydrophobic SDBS-PbO2 anode for electrochemical degradation of nitrobenzene in aqueous solution", 18 June 2018, Electrochimica Acta, 282, 662-671. (Year: 2018) * |
Farhat et al, "Removal of Persistent Organic Contaminants by Electrochemically Activated Sulfate", 17 November 2015, Environmental Science & Technology, 49, 14326-14333. (Year: 2015) * |
Also Published As
Publication number | Publication date |
---|---|
WO2020041712A1 (en) | 2020-02-27 |
EP3841069A4 (en) | 2022-05-04 |
EP3841069A1 (en) | 2021-06-30 |
AU2019325635A1 (en) | 2021-02-11 |
CA3107792A1 (en) | 2020-02-27 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20230331595A1 (en) | System and Method for Electrochemical Oxidation of Polyfluoroalkyl Substances in Water | |
US20220402794A1 (en) | Pfas treatment scheme using separation and electrochemical elimination | |
Shi et al. | Degradation of perfluorooctanesulfonate by reactive electrochemical membrane composed of magneli phase titanium suboxide | |
Lin et al. | Electrochemical mineralization of sulfamethoxazole by Ti/SnO2-Sb/Ce-PbO2 anode: kinetics, reaction pathways, and energy cost evolution | |
Fan et al. | Electrochemical denitrification and kinetics study using Ti/IrO2–TiO2–RuO2 as the anode and Cu/Zn as the cathode | |
Kamaraj et al. | Adsorption of herbicide 2-(2, 4-dichlorophenoxy) propanoic acid by electrochemically generated aluminum hydroxides: an alternative to chemical dosing | |
CN102701329B (en) | Preparation method of porous nanometer crystal electrodes and application of porous nanometer crystal electrodes | |
Niu et al. | A high activity of Ti/SnO2-Sb electrode in the electrochemical degradation of 2, 4-dichlorophenol in aqueous solution | |
Contreras et al. | Electro Fenton removal of clopyralid in soil washing effluents | |
CN104529031B (en) | From sewage, reclaim the method for perfluorochemical | |
Wirzal et al. | Degradation of ampicillin and penicillin G using anodic oxidation | |
CN110526343A (en) | A kind of electro-catalysis coupling advanced oxidation system and its application | |
KR101733020B1 (en) | Apparatus and method for water treatment using oxidation and reduction of manganese dioxide catalyst | |
Mazierski et al. | Role of operating parameters in photoelectrocatalytic degradation of anticancer drugs: Ifosfamide, 5-fluorouracil and imatinib using CdS/TiO2 | |
KR20200103327A (en) | Treatment system for volatile organic compounds | |
CN209065489U (en) | It is a kind of for handling the three-dimensional electrocatalysis oxidation apparatus of ammonia nitrogen waste water | |
Broman et al. | Destruction of per-and polyfluoroalkyl substances (PFAS) via lacasse enzymatic degradation and electrochemical advanced oxidation | |
JP2004122032A (en) | Water purifying treatment system | |
Appia et al. | Electrooxidation of simulated wastewater containing pharmaceutical amoxicillin on thermally prepared IrO2/Ti electrode | |
Brinzila et al. | Electrochemical degradation of pharmaceutical compounds as tetracycline in aqueous solution with BDD electrode | |
KR102065713B1 (en) | Method for treating wastewater from flue gas desulfurization using electrolysis device | |
Smith | Innovative treatment technologies for PFAS-contaminated water | |
JP2904003B2 (en) | Wastewater electrolytic treatment method and anode used for the electrolytic treatment | |
Yu et al. | Electrochemical Degradation of Ammonia Nitrogen in Mariculture Wastewater Using an Activated Carbon Fiber Composite Anode | |
Toma et al. | Targeted electrochemical reduction of carcinogenic N-nitrosamines from emission control systems within CO2 capture plants |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: JPMORGAN CHASE BANK, N.A., AS COLLATERAL AGENT, NEW YORK Free format text: SECURITY INTEREST;ASSIGNORS:EVOQUA WATER TECHNOLOGIES LLC;NEPTUNE BENSON, INC.;REEL/FRAME:055848/0689 Effective date: 20210401 |
|
AS | Assignment |
Owner name: NEPTUNE BENSON, INC., RHODE ISLAND Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:JPMORGAN CHASE BANK N.A., AS COLLATERAL AGENT;REEL/FRAME:063787/0943 Effective date: 20230524 Owner name: EVOQUA WATER TECHNOLOGIES LLC, PENNSYLVANIA Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:JPMORGAN CHASE BANK N.A., AS COLLATERAL AGENT;REEL/FRAME:063787/0943 Effective date: 20230524 |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: NON FINAL ACTION MAILED |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: RESPONSE TO NON-FINAL OFFICE ACTION ENTERED AND FORWARDED TO EXAMINER |